With Americans increasingly disenchanted with the situation in Iraq and President Bush saddled with low job-approval ratings, Democrats mounted their strongest challenge to Republican control of Congress in a dozen years. The voting was widely seen as a gauge of public sentiment on national issues, including the war and Bush's leadership.

Turnout was reported to be relatively heavy in some places, with lines forming soon after polls opened in Virginia, Maryland, Ohio and other states with competitive races.

Some of the longer waits were attributed to technical glitches with new electronic voting machines in several states. Balloting was delayed in dozens of precincts in Indiana, Ohio, Illinois, Pennsylvania and Colorado, forcing election officials to extend polling hours in some places. However, the computer problems and other delays did not appear to be widespread or politically motivated, election monitors said.

Polls closed at 6 p.m. EST in Indiana and Kentucky and at 7 p.m. or 8 p.m. EST in most eastern, southern and Midwestern states. Polls closed at 11 p.m. EST in California, Washington and Hawaii and midnight EST in Alaska.

At stake in Tuesday's elections were all 435 seats in the House of Representatives and 33 of the 100 seats in the Senate. In addition, voters in 36 states were electing governors.

The elections offered Democrats a chance to take control of Congress for the first time since they lost the House and Senate in a 1994 Republican landslide. The GOP has held the House ever since, and the Senate has been under Republican control since then, except for a 19-month period in 2001 and 2002 when a GOP senator quit the party to become an independent.

According to exit polling reported by CNN, national issues were much on voters' minds Tuesday, with corruption, terrorism, the economy and Iraq topping the list of concerns. Belying the bromide that all politics is local, 62 percent of those polled said national issues were the biggest factors in determining their choices, while 33 percent cited local issues.

Voters' emphasis on corruption and Iraq appeared to be good news for Democrats, given a slew of scandals that have dogged Republican lawmakers and the growing unpopularity of the war in Iraq. On the other hand, Bush and his fellow Republicans have touted economic gains and their commitment to the war on terrorism as reasons to stick with a GOP-controlled Congress.

In Indiana, Republican Sen. Richard Lugar cruised to reelection as expected against a Libertarian candidate, and in Vermont, Rep. Bernard Sanders, an avowed socialist running as an independent, easily won the Senate seat vacated by the retirement of James M. Jeffords, a former Republican who became an independent in 2001. The win by Sanders made him the first socialist to be elected to the Senate.

In West Virginia, Sen. Robert C. Byrd, a Democrat who turns 89 later this month and is the longest-serving current member of Congress, won reelection handily.

Also winning reelection to the Senate were Republican Olympia Snowe in Maine and Democrats Edward M. Kennedy in Massachusetts and Bill Nelson in Florida. Nelson defeated Rep. Katherine Harris, a Republican who, as Florida secretary of state, presided over the hotly contested election in the state that gave the presidency to Bush in 2000.

In Ohio, Democrat Ted Strickland defeated Republican J. Kenneth Blackwell in the race for governor, capitalizing on popular discontent over the scandal-plagued administration of outgoing Republican Gov. Bob Taft.